Scale build up around waterfall

[btz30]

Hey everyone. We put our pool in last year and are about 1/2 way through our 2nd summer with it. I've been using the TFP tools and methods (Pool Math app, Taylor K-2006C test kit, etc) the entire time. Thank you to everyone for providing these awesome resources and methods! Things have gone well overall, but late last season I noticed some scale building up on the rock and fiberglass pool surface around our waterfall features. I thought it may have been due to some early chemical imbalance and hoped it would go away, but I've keep things pretty well in balance all season and it has continued to get worse. Below are some photos.

Some basic info:

• Location - central PA
• Pool type - Fiberglass
• Sanitizer - SWG
• Typical FC - 1-2 ppm
• Typical pH - 7.5
• Typical TA - 100-110 (I know this is a little high but has been tough to drive down)
• Typical CH - 350
• Typical CYA - 60

The scale is white and very difficult to remove from the fiberglass and stone in areas where it is a thin film. In areas where it has built up a thicker coating, I can scrape or brush some of it off with a heavy bristle brush or plastic scraper. But this just takes it down to a thinner layer and still looks bad. I've tried sanding it off the fiberglass surface using automotive 1000-2000 grit sandpaper. That works OK, but is very slow going and I worry about damaging the fiberglass. I have no idea how to clean the stone surface...

Questions to you all:

1. What is this substance?
2. What can I do to clean or remove it?
3. How can I take action to reduce or eliminate further build up?

Thanks so much!

 

[mknauss]

Welcome to the forum.
Some of that is efflorescence. Hard to stop that.

See Waterline Scale Removal - Further Reading and Efflorescence - Further Reading

 

[Nikilyn]

I’ve had a hard time getting my TA down. I read on here to bring ph down to 7.2 and then aerate it up. That wasn’t working. Well, someone told me earlier this week to bring it down to at least 7 and then don’t let it get above 7.5. It dropped mine to 60 in a day. It was awesome !